The present invention relates to packaging and more particularly to a device for wiping down a web wrapped on a load.
Machines which are designed to wrap a load with a stretched web to cover and contain the load with a stretched layer of film are generally known as stretch wrapping machines. Examples of such machines are disclosed in U.S. Pat. Nos. 4,232,501 and 4,300,326 to Stackhouse and assigned to Lantech, Inc. These patents and the U.S. patents cited in these references are incorporated herein by reference.
After automatically wrapping a load with a film web, the trailing end of the web needs to be wiped down on the load so that it comes in contact with and becomes adhered to an underlying layer of web. In the past, such wipe down arrangements involved the use of a bristle brush attached to a support which moved relative to the trailing end of the web and the load such as the arrangement shown in U.S. Pat. No. 4,232,501.
However, such arrangements, while effective, offer a number of drawbacks. Bristle brushes provide optimum stiffness only within a very narrow range of distances from the load. As a result, the positioning of the conventional bristle brush would have to be reset when wrapping loads of various sizes. This drawback is of particular significance in automatic, continuous wrapping procedures which would otherwise need little intervention by a human operator.
Another drawback of conventional brush arrangements is that the brush would generally need to be articulated about more than one axis in order to adequately position the brush relative to the wrapped load.
An additional drawback of conventional bristle brushes is that the bristles fatigue, bend and sag after a period of use and therefore need to be replaced after such periods of use.
A further drawback of the conventional brush arrangements is that the brush does not conform to the surface of products having a non-regular shape and, as a result, do not insure a complete wipe down along the whole width of the trailing end of the web.
Another drawback of conventional brush arrangements is that the brush needs to encounter the web at a particular angle and with a particular motion in order to effectively wipe down the web and prevent the bristles from piercing and tearing the web.
Accordingly, it is an object of the present invention to provide a wipe down device which has an extended range over which it can reach automatically in order to accommodate loads of varying sizes.
It is another object of the present invention to provide a wipe down device which does not fatigue or bend vertically after an extended period of use.
It is a further object of the present invention to provide a device which conforms to irregularly shaped products to insure wipe down along the whole width of the web.
It is another object of the present invention to provide a simple relative motion between the wipe down device and the web and load.
It is an additional object of the present invention to provide a wipe down device which effectively wipes down the trailing end of the film web over a wide range of angles and wiper wipe down motions without piercing or tearing the web.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.